import java.util.LinkedList;
import java.util.Queue;

public class test {
    public static void main(String[] args) {
        Queue<Integer> q = new LinkedList<>();

        q.offer(1);
        q.offer(2);
        q.offer(3);
        q.offer(4);
        q.offer(5);

        System.out.println(q.size());
        System.out.println(q.peek());

        q.poll();
        System.out.println(q.poll());

        if(q.isEmpty()) {
            System.out.println("队列为空");
        } else {
            System.out.println(q.size());
        }
    }
}
